The present invention relates to a communication line adapter and the method thereof that adapts a main controller including data base and a computer to a public telephone network to communicate with a plurality of terminals connected to the public telephone network.
A general main controller such as data base and computer system needs a communication device such as a modem to communicate data with a remote terminal connected via a public telephone network and control the terminal. However, the communication device has to keep being connected to a main controller to match the main controller to the public telephone network, so that the main controller cannot communicate with a plurality of terminals. The problem of the above communication device is described with reference to FIG. 1.
With reference to FIG. 1, a communication device including a modem, connected between a computer system and a public telephone network 11 is shown. The communication device modulates digital control command and digital data supplied from the computer system 10 into analog signal, and transmits the modulated analog signal to a terminal (not shown) via the public telephone network 11. The communication device 12 demodulates the digital data included in the analog signal coming from the terminal through the public telephone network 11 and transmits the demodulated digital data to the computer system 10. The conventional communication adapter including the modem has to keep being connected to the computer system 10 to modulate the digital data and demodulate the digital data loaded on the analog signal, so that it makes the main controller not be communicated with the plurality of terminals. The conventional communication device cannot communicate with the terminal when the transmission speed of terminal is not equal to that of communication device or when a modem is not included in the terminal.